The present invention relates to a process for the production of hollow bodies of revolution formed from wires, filaments or threads extending in three different directions. The invention also relates to a machine for performing this process.
The directions of the wires constituting the body of revolution are substantially radial, axial and circumferential, which can in certain cases be substantially different from the corresponding geometrical directions.
The production of such three-dimensional woven bodies or parts can take place with any type of thread or wire and particularly those made from glass, carbon, graphite, ceramic materials, etc. Therefore, in this sense the term thread will be used herein to designate fibres, wires, wicks, strands, woven fibres, etc.
It is presently known to install or implant retaining or locking rings radially on a support mandrel from a material permitting said installation, so as to define between said rings longitudinal and circumferential passages, in which are then placed by winding and weaving layers of superimposed threads, after which the support mandrel is removed. Such a process is more particularly known from French patent No. 2 408 676, filed on Sept. 23, 1977 by the Commissariat a l'Energie Atomique.
An improvement to this process was proposed in French patent application No. 81 13868 filed on July 16, 1981 by the Commissariat a l'Energie Atomique. This improvement relates to the installation of the retaining rings and, as a result of a prior perforation of the mandrel, makes it possible to install in a satisfying manner larger retaining rings.
Despite the advantages offered by these processes and the machines ensuring the performance thereof, certain problems still occur, particularly when it is wished to significantly increase the dimensions of the bodies to be produced and also when modifying the shapes thereof.
Thus, the means normally used for winding and weaving the threads in the passages formed between the retaining ring generally comprise a weaving carriage which moves permanently in parallel to the mandrel axis. During the machining of non-cylindrical parts, such as those which are conical, truncated cone-shaped or having even more complex shapes, the unwinding of the weft on leaving the weaving means takes place under different conditions as a function of whether said means moves in one or other direction, because said means is oriented perpendicular to the weaving carriage. Moreover, in the case of a large non-cylindrical part, this can lead to not placing the weft between the wedges, but beyond the latter on a lengthwise portion of the part.
Furthermore, the presently known processes involve the successive use of several different machines. Thus, it is necessary to successively use a machine for machining the support mandrel, a machine for installing the retaining rings on said mandrel and a machine for the winding and weaving of the threads in the passages formed between the rings. Apart from the obvious disadvantages linked with the number of machines used (cost, maintenance, personnel, etc.), it should be noted that the increase in the dimensions of the parts leads, in the case of equal tolerances, to it being more difficult to control each of the machines so as to take account of the operation performed by the preceding machine. Thus, in particular as the dimensions of the part increase, it becomes more difficult to adjust the spacings of the winding and weaving as a function of the spacing of the installation of the retaining rings.
Finally, it should be noted that at present no machine is known which makes it possible to produce hollow parts or bodies of revolution which can be up to 1500 mm long and which can have an external diameter varying between 60 to 2100 mm.